Severe hyperthermia can be lethal; however, lesser hyperthermic shock can protect against this lethality. Hyperthermic shock can cause the reversible arrest of growth and development. At the molecular level, hyperthermic shock induces the synthesis of "heat shock proteins" (hsps). We believe the hsps mediate the effects of protection from severe shock, and of reversible growth arrest. The mechanisms may be related to those of viral carcinogenesis, which has been shown to interrelate with certain hsps. We propose to dissect the hsp induction system of Drosophila, in an effort to learn what aspects of cellular metabolism are critical to, and affected by, the hsp induction system. In vitro induction of hsp gene transcription (polytene chromosome puffing) will form a functional assay for several aspects of the response. We will isolate and characterize hsp84, the hsp most likely involved in mediating the cytoplasmic aspects of the hyperthermic response. We will perform a detailed genetic analysis of hsp84 to determine its role in vivo, and begin genetic analyses of other aspects of the response. We hope to gain an understanding of how cytoplasmic metabolism integrates with transcriptional control, and how, through hsp production, growth and development can be controlled.